ctva
Well-Known Member
Just wondering...
PS, the boat is kept in fresh water and used in salt.
PS, the boat is kept in fresh water and used in salt.
What happens if I put a zinc and aluminium anode on the same shaft?
- Thread starter ctva
- Start date
Hacker
Well-Known Member
On what type of hull?
Momac
Well-Known Member
The aluminium anode will deplete and the zinc will not (probably).
Don't mix anodes
Don't mix anodes
vyv_cox
Well-Known Member
It's not such an easy question to answer
In fresh water a zinc anode slowly passivates due to the formation of surface zinc hydroxide. If the boat had been in fresh water for some time before going to sea the aluminium anode would protect the prop/shaft couple.
If the boat went to sea before the film formation the zinc would protect the aluminium and probably the prop/shaft but would corrode more quickly.
Advice now is that aluminium anodes are preferred over zinc for almost all duties. The time is coming when zinc will be phased out. Unfortunately specialised anodes such as Bruntons prop anodes are not yet available in aluminium (when I last looked). I wrote an article on this subject for YM a year or two ago.
In fresh water a zinc anode slowly passivates due to the formation of surface zinc hydroxide. If the boat had been in fresh water for some time before going to sea the aluminium anode would protect the prop/shaft couple.
If the boat went to sea before the film formation the zinc would protect the aluminium and probably the prop/shaft but would corrode more quickly.
Advice now is that aluminium anodes are preferred over zinc for almost all duties. The time is coming when zinc will be phased out. Unfortunately specialised anodes such as Bruntons prop anodes are not yet available in aluminium (when I last looked). I wrote an article on this subject for YM a year or two ago.
ctva
Well-Known Member
Thanks. Should have said it’s an AWB. At present there is a nearly whole zinc anode on which I will replace with an alu one so seeing if it would be worth leaving the zinc one on for as long as t lasted.